The invention relates generally to supplied air respirators and more particularly to a respirator which has a removable air baffle which increases the air flow efficiency without increasing the operating noise level of the respirator.
In various water and air borne pollutant environments, such as a nuclear, welding, fiberglass, asbestos, grain bin and other pollutant containing environments; it is desired to have the workers shielded at least from breathing or otherwise contacting the pollutants. Supplied air respirators are designed to be utilized in these environments which are non-catastropic work areas. In otherwords, the respirators are utilized to protect against the long term affects and the worker could take a failed respirator off and leave the work area without serious damage. The respirator may be a hood, full suit or other type of wearing apparel.
One type of respirator is a full face respirator which is sealingly engaged like a mask on the head of the worker to cover the facial areas including the eyes, nose and mouth. There are numerous disadvantages in using this type of mask, including: training the workers, a reduced field of vision, claustrophobia, leakage, discomfort and decontaminating and cleansing the mask each time utilized which increases costs. Further, the mask does not fit all facial sizes and shapes, especially workers with beards.
It thus would be desirable to eliminate the disadvantages of the full face respirator to increase comfort, wearability, air flow, etc. To attempt to overcome these disadvantages, hood type sypplied air respirators have been developed.
One type of hood type supplied air respirator has been developed having a foam air distribution block in the top of the hood or headpiece which includes an air supply hose sealed to the hood and secured into the air block. The air filters through the foam block at the top of the hood above the worker's head. This provides a cooler and more comfortable working environment than the full face respirator. A disadvantage of this unit is the added bulk of the foam block in the top of the hood which also does not permit the worker upward vision through the top of the hood. The block is not removable so that the respirator and air supply both must be disposed of after each contaminating use where it not possible or expedient to decontaminate the respirator. The contaminating use would be in an environment such as a radioactive environment where the outside of the hood becomes contaminated or sufficiently dirty that it cannot be reused or revitalized.
A second type of supplied air respirator with hood has a removable baffle system, but has a high back pressure which reduces the air flow efficiency of the system. NIOSH (National Institute for Occupational Safety and Health) have set standards for the operation of the respirators to supply a minimum of 6 cubic feet per miniute (cfm) of air and a maximum of 15 cfm of air and less than or equal to 80 decibels noise with an operating back pressure of 1 inch of water or less. Also the operating noise level at 15 cfm is close to the 80 decibel allowed maximum. This respirator has a baffle including a slitted tube wrapped with a gauze tape with cloth wrapped around the gauze tape. The life expectancy of the baffle is expected to be reduced since the gauze tape is affected with moisture and may loosen in use. The noise level which intially is close to the allowed maximum would appear to be increased by any loosening or other deteriation of the gauze type tape. The high back pressure appears to be caused by the tape compressing the tube slits. This is a problem where the work space or plant in which the worker is located has a low pressure air supply and the back pressure may result in the respirator air supply being below the minimum of 6 cfm.